This invention relates to a submersible mixing propeller used to introduce and mix a fluid (air, other suitable gasses and/or liquids) into liquids and to mix liquids and solids in those liquids.
Submersible mixing propellers are used as an aerator to aerate a liquid (that is introduce fine bubbles of air, or other gas, to intermix with the liquid) while simultaneously mixing the liquid with the air (or other gas) and also mixing the liquid (including solids suspended therein) into which the propeller is submerged. They are commonly used in industrial applications, including in waste water treatment plants to mix and aerate the waste liquids to facilitate digestion of waste in those liquids. It is important in achieving maximum efficiency of the digestion process to provide significant mixing of the waste water liquid and solids contained therein as well as to introduce air or other suitable gasses into the waste water in a manner which facilitates the mixing of the air or other suitable gasses with the waste water. Preferably the mixing propeller not only causes significant mixing of the liquids and solids, but also introduces the air and/or other suitable gases into the liquid in fine bubbles to assist in the absorption process with the liquid. The air and/or other suitable gasses suspended in the liquid is important as oxygen in the air or other suitable gasses is used by bacteria and other microscopic organisms in the process of digestion of the waste solids and decomposition of organic matter in the water in order to clean the water.
Such propellers can also be immersed into a first liquid and used to introduce and mix a second liquid into the first liquid. A mixture of air (or other gas) and a second liquid may also be introduced and mixed with the first liquid.
The application is also directed to a propeller that is suspended in a liquid to both mix that liquid and introduce fluids into the liquid in a manner which maximizes the absorption of the fluids into the liquid. The propeller is designed to provide both axial and radial flow to the liquid. Openings in the propeller for introducing fluid into the liquid are positioned optimally, as are the blades with respect to each other, to ensure the creation of fine bubbles of air or gas discharged into the liquid to physically contact the propeller as it spins. The shape of the blades of the propeller further assist in the mixing and aerating process undertaken by the propeller, the suction of fluid from the propeller openings into the liquid, and the axial and radial flow caused by rotation of the propeller.
It should be understood that while the term “air” is used in this description that term includes any other suitable gas or mixtures of gases as would be apparent to one skilled in the art. Similarly the use of the term “gas” includes air and any suitable mixtures of gases. The use of the term “fluid” means either a gas (including air), a liquid or a mixture of gas and liquid.
In an aspect of the invention a submersible mixing propeller for dispersing and mixing a fluid in a liquid, the propeller having an axis of rotation, includes an input for receiving a flow of fluid, first and second blades having a pressure side, suction side, tip, root section, leading face and a trailing face and a chamber communicating with the input for receiving the flow of fluid from the input. The trailing face comprises a first opening extending into the chamber to permit the flow of fluid in the chamber to exit the propeller. The tip comprises a second opening extending into the chamber to permit the flow of fluid in the chamber to exit the propeller. The suction side is angled from a plane perpendicular to the axis of rotation in a direction toward the pressure side when moving from the leading face to the trailing face. The first opening of the first blade is aligned generally in the same plane with the leading face of the second blade which follows the first blade, when the propeller is rotated.
In a further aspect of the invention the leading face is curved rearwardly along its length in a direction away from the direction of rotation of the propeller.
In another aspect the width of the leading face is greater than the width of the trailing face such that the pressure side and suction side are closer together at the trailing face as compared to the leading face.
Optionally, the pressure side is angled from a plane perpendicular to the axis of rotation in a direction toward the suction side when moving from the leading face to the trailing face. The angle of the suction side from the said plane may be greater than the angle of the pressure side from the said plane.
In a further embodiment the suction side is located at a lower region of the blade and is angled upwardly and the pressure side is located at an upper region of the blade and angled downwardly. The suction side may be located at an upper region of the blade angled downwardly and the pressure side may be located at a lower region of the blade angled upwardly.
In a further aspect of the invention the trailing face is curved rearwardly along its length in a direction away from the direction of rotation of the propeller and wherein the amount of curvature of the leading face is less than the amount of curvature of the trailing face such that the distance between the leading face and the trailing face is greater at the tip as compared to the root section of the blade.
In another embodiment the first opening of the first blade is configured to direct the flow of fluid from the chamber rearwardly in a direction away from the direction of rotation of the propeller to contact the leading edge of the second blade. Optionally, the second opening of the first blade is configured to direct the flow of air from the chamber radially and rearwardly to contact the leading edge of the second blade.
The number of blades may be four, oriented symmetrically about the axis of rotation.
In another embodiment the suction side is angled sufficiently to provide axial flow of the liquid when the propeller is rotated. The angle may between 5 degrees and 17 degrees from the said plane. The angle may be about 6.95 degrees from the said plane.
As a further embodiment the angle of the suction side from the said plane is greater than the angle of the pressure side from the said plane wherein the pressure side is angled sufficiently to provide axial flow of the liquid when the propeller is rotated. The angle may be between 1 degree and 10 degrees from the said plane. The angle may be about 1.30 degrees from the said plane.
In a further embodiment the plane defined by the leading face is oriented generally parallel with the axis of rotation of the propeller.
In another embodiment the plane defined by the trailing face is oriented generally parallel with the axis of rotation of the propeller.
In another embodiment the width of the blade between the leading face and the trailing face at the tip is greater than the width of the blade between the leading face and the trailing face at the root section.
In another embodiment an submersible mixing propeller adapted to be rotated about a central axis, includes an intake, a plurality of hollow propeller blades radially extending outwardly from the central axis and connected to the intake, the propeller blades having a pressure side, suction side, tip, root section, leading face and a trailing face. The pressure side is oriented at an angle from a plane perpendicular to the axis of rotation in a direction toward the suction side when moving from the leading face to the trailing face. The suction side is oriented at an angle from a plane perpendicular to the axis of rotation in a direction toward the pressure side when moving from the leading face to the trailing face. A first discharge opening in the trailing face and a second discharge opening in the tip are also provided. The trailing face of a first blade is aligned generally in the same plane with the leading face of the second blade which follows the first blade such that when the propeller is rotated in use liquid exiting the discharge opening of the first blade is struck by the leading edge of the second blade. The angled orientations of the pressure side and the suction side cause an axial flow of the water in which the propeller is submersed.
In a further embodiment of the invention a mixer for aerating and mixing a liquid includes a propeller, a shaft connected to the propeller, a motor connected to the shaft for imparting rotational force from the motor to the propeller through the shaft, a conduit in the shaft for transmitting a flow of gas to the propeller. The propeller includes at least one blade having a pressure side, suction side, tip, root section, leading face and a trailing face. The propeller includes a chamber connected to the conduit for receiving a flow of gas from the conduit. The trailing face includes a first opening extending into the chamber to permit the flow of gas in the chamber to exit the propeller. The tip includes a second opening extending into the chamber to permit the flow of gas in the chamber to exit the propeller. Optionally the shaft comprises an intake opening for receiving the flow of gas into the conduit in the shaft.